[MAPREDUCE-6918] ShuffleMetrics.ShuffleConnections Gauge Metric Climbs Infinitely

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Component/s: mrv2
• Assignee: Unassigned
• Reporter: Erik Krogen
• Created: 25/Jul/17 23:42
• Updated: 27/Oct/17 17:15
• Resolved: 27/Oct/17 17:15

Description

We recently noticed that the mapred.ShuffleMetrics.ShuffleConnections metric seems to climb infinitely, up to many millions (see attached graph), despite being supposedly a gauge measure of the number of open connections:

ShuffleHandler.java

    @Metric("# of current shuffle connections")
        MutableGaugeInt shuffleConnections;

It seems that shuffleConnections gets incremented once for every map fetched, but only decremented once for every request. It seems to me it should be modified to only be incremented once for every request rather than for every map fetched, but I'm not familiar with the original intent.

Issue Links

• duplicates: MAPREDUCE-6919 ShuffleMetrics.ShuffleConnections Gauge Metric Rises Infinitely